CVE-2025-21518 is a medium-severity vulnerability identified in the Oracle MySQL Server product, particularly within the Server: Optimizer component. This vulnerability allows a low privileged attacker with network access via multiple protocols to compromise MySQL Server. Affected versions include MySQL 8.0.40 and prior, 8.4.3 and prior, and 9.1.0 and prior. This flaw can lead to unauthorized denial-of-service (DoS) conditions, where successful exploitation may cause the MySQL Server to hang or crash frequently, significantly impacting availability. The CVSS 3.1 Base Score for this vulnerability is 6.5, indicating that it poses a moderate risk to organizations.
Given the availability impact, organizations should prioritize patching immediately. The vulnerability's ease of exploitation increases the urgency for defenders to assess their systems and apply the necessary updates to mitigate the associated risks.
The vulnerability was published on January 21, 2025, and has since been modified with ongoing updates. Organizations must stay informed about any changes in the vulnerability's status and the availability of patches to ensure their systems remain secure.
Risk to organizations includes potential downtime and loss of service availability, which could impact business operations and customer trust. Therefore, immediate action is recommended to address this vulnerability.
Vulnerability Details
The official CVE description states that this vulnerability allows a low privileged attacker to compromise MySQL Server via network access. The attack vector is categorized as NETWORK, with a low attack complexity requirement and no user interaction necessary. The CVSS score of 6.5 reflects a high availability impact, while confidentiality and integrity impacts are rated as none. The affected products include MySQL Cluster and MySQL Server, with versions up to 8.0.40, 8.4.3, and 9.1.0.
The vulnerability falls under CWE-770, which indicates a flaw related to improper handling of resource management.
Technical Analysis
The root cause of CVE-2025-21518 stems from the MySQL Server's inability to appropriately manage network requests, leading to resource exhaustion. The attack vector is primarily network-based, allowing attackers to exploit the vulnerability remotely without requiring physical access to the server.
The attack complexity is classified as low, as it does not require advanced skills or significant resources to exploit. Additionally, the attacker does not need elevated privileges to initiate an attack, facilitating easier exploitation. User interaction is not required, further increasing the risk.
The availability impact is rated high, as successful exploitation can lead to a complete denial of service, effectively causing the MySQL Server to hang or crash. This vulnerability poses a critical risk to any organization relying on MySQL for database management.
Risk & Impact Analysis
Organizations using affected versions of MySQL Server are at significant risk of service disruption. The potential for a denial of service means that critical applications dependent on MySQL could experience outages, leading to financial and reputational damage. This vulnerability is particularly concerning for high-availability environments where uptime is crucial.
With a CVSS score of 6.5, this vulnerability is classified as medium severity, warranting prompt attention. Its inclusion in the Common Vulnerabilities and Exposures (CVE) database signals widespread recognition of the risk, and organizations should take this seriously. The EPSS score of 0.0017 indicates a low probability of exploitation in the wild, but this does not diminish the importance of addressing the vulnerability.
The urgency for remediation should be aligned with the potential impact of a successful exploit. Organizations should consider their dependency on MySQL Server and the potential fallout from a service interruption when prioritizing their patching schedule.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The following versions of Oracle MySQL are affected by CVE-2025-21518:
• MySQL Cluster: Versions 8.0.40 and prior, 8.4.3 and prior, 9.1.0 and prior.
• MySQL Server: Versions 8.0.40 and prior, 8.4.3 and prior, 9.1.0 and prior.
Mitigation & Remediation
Organizations should prioritize patching their MySQL installations to the latest versions as a remediation measure. The patches are made available by Oracle, and the specific version to upgrade to should be identified based on organizational requirements.
In cases where immediate patching is not feasible, organizations should implement workarounds to limit exposure, such as restricting network access to the MySQL servers or employing network security controls to monitor and mitigate potential exploit attempts.
Configuration hardening should also be considered, ensuring that MySQL servers are not exposed to unnecessary network interfaces. Regular monitoring of logs for unusual activity can help identify potential exploitation attempts.
Organizations may benefit from continuous security testing to identify and address similar vulnerabilities.
Detection Guidance
To detect potential exploitation of CVE-2025-21518, organizations should monitor logs for unusual patterns of connection requests or abnormal server responses. Behavioral anomalies indicating service unavailability or repeated connection failures may also signal an attack in progress.
Network signatures that correlate with known attack patterns can aid in identifying intrusion attempts. It is also critical to observe any changes in system performance or unexpected server behavior that could indicate a successful exploit.
AppSecure Threat Intelligence Insight
CVE-2025-21518 highlights the ongoing need for organizations to maintain robust security practices around database management systems. As cyber threats evolve, the ability to quickly identify and remediate vulnerabilities becomes increasingly critical.
This vulnerability serves as a reminder that even widely used products like MySQL can harbor significant risks. Security teams must ensure that they regularly update their systems and incorporate vulnerability management programs into their operations to stay ahead of potential threats.
To further enhance security posture, organizations should consider leveraging application security assessments and investing in red teaming services to test the effectiveness of their defenses.
Regular updates and proactive security measures can help mitigate risks associated with vulnerabilities like CVE-2025-21518 and ensure that organizations remain resilient against evolving threats.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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